A conventional clip of this type, although not specifically illustrated in the drawings, is molded from a synthetic resin as a single piece, consists of a head portion and a shaft portion extended from a lower surface of the head portion, and is constructed such that radially extending elastic blades are provided in multiple stages along the vertical direction on opposing outer peripheral surfaces of the shaft portion (e.g., refer to patent document 1).
In a case where a roof trim, which is an upholstery material of an automobile, is fixed to a roof panel by using this conventional clip, the roof trim is superposed on the roof panel to obtain a state in which their mounting holes are aligned, and the shaft portion is pressed into the mounting holes. Then, in the process in which the elastic blades are passed through the mounting holes, the elastic blades are pressed and curved by inner peripheral surfaces of the mounting holes, and the elastic blades after passing to the reverse surface side of the mounting holes return to their original state, thereby preventing the shaft portion from coming off the mounting holes. As a result, the roof trim is fixed to the roof panel.
Patent document 1: JP-A-8-159125